Jim Lesurf wrote:
Two follow-on issues I want to raise:

But it doesn't work on another machine.

The machine where it fails to run is one which I installed xfce Mint
18.1 onto a few days ago. (32 bit version as it has a 32 bit cpu)

On that, when I try to run the ffmpeg executable I get

Error while loading shared libraries: libgnutls.so.26: cannot open
shared object: no such file or directory.

I assume this means it can't find libgnutls.so.26 ?

Others have already answered really, but you can't really move binaries
about easily when 64bit/32bit are involved.

FWIW ... no such file or directory is the error you will get when mixing
32bit/64bit around so that error probably doesn't mean that gnutls is
not found.

TBH, I know nothing about multilib - pure 64bit LFS here, far too lazy
to do multilib LFS just for steam/old games, which is about all I miss
out on.